    Patent literature 1: JP 5482055 B (corresponding to US 2012/0176115 A1)    Patent literature 2: JP 2013-85443 A (corresponding to US 2013/0063850 A1)
For example, patent literature 1 and patent literature 2 each describes an overcurrent protection circuit that protects a protection target from overcurrent. The overcurrent protection circuit detects current flowing through a semiconductor switch for switching current supply to a load. Based on the detected current, the overcurrent protection circuit turns off the semiconductor switch when overcurrent has been detected, so that, for example, a wire is protected from fuming (or smoking). Specifically, a sense current is obtained by reducing a current flowing through the semiconductor switch at a predetermined ratio. The sense current is converted to voltage with an I-V conversion circuit, and an AD converter (an analog-to-digital converter) converts voltage being an analog value after conversion to a digital value. A controller such as a microcomputer determines an addition value corresponding to the digital value. The controller cuts off current by turning off the semiconductor switch in a case when an integration value of the addition value exceeds a determination threshold.